The European Green Deal aims at a 90 % reduction in transport emissions to achieve climate neutrality by 2050. To this end, sustainable aviation fuels (SAFs) are essential. The EU / SERI-funded project SUN-to-LIQUID II addresses this challenge with solar-thermochemical technology that has the potential to produce sustainable and cost-effective fuels at the scale of future demand directly from concentrated sunlight, water, and CO2. Bauhaus Luftfahrt is coordinator and research partner in the consortium of three research organisations, two SMEs, and one industry partner from five European countries.
This project builds on the achievements of its predecessors SOLAR-JET and SUN-to-LIQUID. SUN-to-LIQUID II aims to demonstrate the viability of the integrated solar fuel pathway on a 50-kW scale. The primary objective is to achieve a record-high solar-to-syngas energy conversion of 15 % by bringing novel concepts and lab-scale developments (technology readiness level TRL 2 – 3) to the field (TRL 4 – 5). The project aims to optimize the high-flux solar concentrating heliostat and tower system, develop and integrate novel 3D-structured reactants, and implement high-temperature heat recovery. Future scale-up is investigated by detailed system analyses that will create a conceptual design of a next-generation commercial multi-megawatt-scale solar plant to evaluate life-cycle emissions, cost, and commercial viability.
As a result, SUN-to-LIQUID II should provide significant progress and a clear roadmap toward cost-effective and deep greenhouse gas emission reduction potential especially for aviation, with technical scalability beyond projected future demand.
Methodology and concept
Schematic of a redox cycle which stores concentrated solar energy in liquid hydrocarbon fuels produced from H2O and CO2. This reversal of combustion is accomplished via a two-step thermochemical cycle at high temperatures.
Glossary: SAF sustainable aviation fuel, CO2 carbon dioxide, SMEs small and medium-sized enterprises, TRL technology readiness level
Funded by the Euopean Union: SUN-to-LIQUID II, HORIZON EUROPE and SERI co-funded this project (SERI: State Secretariat for Education, Research and Innovation, Federal Department of Economic Affairs, Education and Research, Swiss Confederation).